Embodiments of the present inventive concepts relate to a method of operating input/output interfaces, and more particularly to a method of operating an input/output interface which may select and use one of a plurality of output driver circuits or one of a plurality of input receiver circuits.
Each of a system on chip (SoC) including a central processing unit (CPU) and a memory controller and a memory device (e.g., main memory), connected to the SoC includes an input/output interface for interfacing mutual data transmission.
According to an increased operation speed, as a swing width of a data signal mutually transmitted and received between the SoC and the memory device gets decreased, not only an influence of external noise gets increased, but also impedance mismatching in the input/output interface may be a problem. In order to solve the impedance mismatching, the input/output interface may include an impedance mismatching circuit which is referred to as On-Die Termination, On-Chip Termination, or On-Board Termination.